Pass unique instanceName in native C implementation "instantiate"
Function "Java_org_simantics_fmil_core_FMIL_instantiateSimulation_1" currently always passes an empty String to fmiInstantiate. This is not acceptable in FMU 2.0 specifications. We should instead pass a unique identifier, such as modelName + (random GUID).
cpp file: org.simantics.fmil.core/native/FMUSimulator/src/fmu_control.cpp